Arinia biplicata Vermeulen, 1996  

Vermeulen (1996) original descriptions on Arinia biplicata – “Shell shortly cylindrical to shortly fusiform, last whorl or last two whorls widest. Whorls 4-4½, moderately convex. Constriction with two high longitudinal ridges, a parietalis and a basalis, both continuing into the tuba and gradually disappearing towards the aperture. Tuba about 3/8-1/2 whorl, with the basal ridge inside impressed as a furrow. Radial ribs single-crested, on the top whorls and the penultimate whorl 16-22 ribs/0.5 mm, above the aperture with 3-6 ribs/0.5 mm. Spiral striation absent or present, fine and inconspicuous. Umbilicus open, 0.15-0.20 mm wide. Aperture not turned upwards, with the basal ridge just visible inside. Peristome: palatal side not protruding beyond the penultimate whorl, columellar side not sinuous; outer peristome slightly to moderately spreading beyond the inner on the palatal and basal side, rather abruptly narrowed on the columellar side and towards the angular edge; inner peristome slightly to moderately protruding from the outer, spreading, just above the angular edge with a ridge oblique to the margin, at the right side of which an inconspicuous furrow, palatal and basal side without a lip parallel to the margin, its outer surface with few fine lamellae.”